A brushless permanent-magnet motor typically includes a control system for controlling the excitation of phase windings of the motor. When driven by an AC supply, the control system often includes an active power factor correction (PFC) circuit, which outputs a regular DC voltage for use in exciting the phase windings. By providing a regular DC voltage, the power of the motor may be relatively well controlled. However, an active PFC circuit significantly increases the cost of the control system. Additionally, the PFC circuit requires a high-capacitance DC link capacitor, which is both physically large and expensive, in order to provide a regular feedback voltage to the PFC circuit.